Process for bleaching tobacco



Patented Aiig. 22, 1939- UNITED STATE.

. PROCESS FOR BLEACHING TOBACCO Herman I many, assignor to Baler, Frankfort-on-the-Main, Ger- Deutsche Gold und Silber Scheideanstalt vorinals Roessler, Frankfort-onthe-Main, Germany,

No Drawing.

al No. 61,053.

4 Claims.

December 28, 1934 and Serial No. 18,879 fi1ed April 28, 1935.

Several processes have been recommended and are now employed'in the treatment of tobacco with hydrogen peroxide. One of these processes is the well-known dipping. process for refining tobacco in which the tobacco is soaked for a certain period of time in an alkaline solution of hydrogen peroxide. Subsequent to this soaking it is removed and dried. Other methods for treating tobacco involve a spraying process. My copending application scribes and claims a method which involves spraying the tobacco with the treating agents.

In the spraying process the tobacco may be treated with an alkaline, preferably 'ammoniacal, solution of hydrogen peroxide which is applied to the leaf or cut tobacco through suitable nozzles. A variant of this process is the ammonia vapor process in which the tobacco is first sprayed with a solution of. hydrogen peroxide and then treated with ammonia vapor. The latter procedure has the distinct advantage that after completion of the bleaching the tobacco is free from hydrogen peroxide, whereas in other processes undecomposed hydrogen peroxide remains on the tobacco.

'However, the use of a process in which the tobacco is subjected to the action of ammonia vapor requires a relatively. complex and expensive apparatus, and its use in many factories would necessitate the scrapping of old equipment and its replacement by new. For these reasons it has been customary in the past to employ one of the other processes which do not require additional plant expense. Indeed the industry has usually preferred the simple spraying process, using an ammoniacal solution of hydrogen peroxide, chiefly for the reason that it may beutilized without materially changing the apparatus now installed in the factories engaged in the processing of tobacco.

After the tobacco is treated with hydrogen peroxide utilizing the spraying method previously referred to, it has been found that some of the hydrogen peroxide still remains undecomposed in or on the tobacco. Just after the treatment is completed the Serial No. 759,597 detobacco still possesses its full a corporation of Germany Application January 27, 1936, Seri- In Germany January 28,

aroma and is very pleasant and mild. However, during the storage period which necessarily occurs after the treatment much of the aroma is lost, and the flavor becomes very much less pleasant when the tobaccois smoked.

The invention with which this. application is concerned is based on the discovery that during storage the quality of the tobacco is impaired by the residual hydrogen peroxide which remains in theundecomposed state on the tobacco at the conclusion of its treatment with the bleaching and refining agent. Research has revealed that the tobacco is capable of chemically combining with the hydrogen peroxide, its ability to do this varying, however, with different types of tobacco. The ability to combine chemically with the peroxide is much more pronounced in tobaccos of.

relatively high aroma than in those which possess a poor aroma. During the storage period the residual hydrogen peroxide gradually decreases, and after a certain period of time no residual hydrogen peroxide remains. The period of time necessary for complete decomposition of the undecomposed hydrogen peroxide depends essentially on the quality of the tobacco. When a mixture of 50% domestic and 50% foreign tobacco is prepared ithas been found that the tobacco must be stored from 4 to 10 days before it is completely free from hydrogen peroxide and of constant chemical composition.

I have now found that all of these changes in the chemical characteristic of the tobacco, with consequent deterioration to its quality, occurring during the storage period, may be avoided if the tobacco is subjected to the action of an agent which causes decomposition of the residual hydrogen peroxide. These agents should be applied at the conclusion of the hydrogen peroxide treatment step. The residual hydrogen peroxide may conveniently be removed either by chemical action such as by reduction or by the action of catalysts. As an agent to react with the hydrogen peroxide and destroy the residual peroxide, sulfurous acid, salts of sulfurous acid such as potassium or sodium bisulfite, a metal permanganate such as sodium or potassium permanmeans of a nozzle or any similar apparatus directly on the tobacco after the peroxide treatment. As an alternative method of applying the glucose, it may be added directly to the tobacco sauce so that the usual ment and the treatment with glucose are carried out in a single operation. These customary tobacco sauces contain or comprise the well known substances which improve the taste or the smell of the tobacco. Such substances are for instance extracts of currants, raisins, cinnamon, aniseed, sugar, glycerine, hygroscopic substances such as calcium chloride, also substances with a disinfecting effect, such as benzoic acid and the' like.

After tobacco has been subjected to the action of hydrogen peroxide, the adhering undecomposed hydrogen peroxide may also be destroyed by contacting the tobacco with certain substances which act catalytically to decompose hydrogen peroxide. The same efiect may be obtained if these substances are added to the tobacco before the tobacco is treated with hydrogen peroxide. as for example, before the tobacco is treated with the tobacco sauce. Any suitable decomposition catalyst for hydrogen peroxide may be utilized and I have found particularly useful cobalt salts, nickel salts, and iron salts. Certain organic catalysts may also be used in the removal of residual hydrogen peroxide, as may ultra-violet light or ozone, both of which also operate to remove or decompose the hydrogen peroxide remaining in the treated tobacco.

By the process described in which the residual hydrogen peroxide is removed from the tobacco after the latter has been subjected to refining action of this oxygen-evolving compound I have found that raw, unpleasant tobacco is transformed into tobacco of a much milder quality which is more desirable for smoking purposes. At the same time the lightened color, attributable to the bleaching action of hydrogen peroxide, is the general smoking public. lighter, milder tobacco prepared in accordance with my process, it has been found that the expensive foreign tobacco now blended with domestic tobacco in the preparation of smoking mixtures may be dispensed with either in whole or in part since domestic tobacco refined in accordance with my process can replace it.

As an example of may be given:

100 kilograms of tobacco are placed in a rotatmy process the following .consisting of 10 liters of tobacco saucing treating tube and sprayed with a bleaching solution 40% hydrogen peroxide solution, 20 liters of water, and 2 liters of 25% ammonia. The solution is applied by means of nozzles. If hydrogen peroxide of lesser concentration is commercially available, an amount greater than 10 liters and sufficient to give approximately the same hydrogen peroxide content can, of course, be utilized.

The tobacco is then dried as usual in a second rotating tube. At the conclusion of the drying step the tobacco, still containing from 0.2 to 0.4% hydrogen peroxide, calculated on the weight of the tobacco,'is sprayed with 10 liters of a solution consisting of 7 liters of water, 2.5 kilograms of glucose and 3.1 liters of. tobacco sauce. At the conclusion of this step the tobacco is again dried found to be considerably improved. The tobacco is much milder and is considerably lightened in color.

Various changes may be made in the process that I have described and in the amounts of reagents that I have given as illustrative which will nevertheless still fall within the scope of my invention. The various details given are to be considered as illustrative and not restrictive and the scope of the invention is to be determined solely in accordance with the appended claims.

I claim:

1. A process of bleaching tobacco which comprises first moistening the tobacco with a solution of hydrogen peroxide and subsequently subjecting said tobacco to the action of a. reducing agent which will reduce and destroy residual hydrogen peroxide.

2. A process for bleaching tobacco which comprises moistening said tobacco with a solution of hydrogen peroxide and then subjecting said tobacco to the action of a solution of glucose for destroying the residual hydrogen peroxide.

3. A process for bleaching tobacco which comprises the steps of spraying the tobacco with a solution of hydrogen peroxide and then spraying said tobacco with a solution of a reducing agent for decomposing the residual hydrogen peroxide.

4. A process for bleaching tobacco which comprises the steps of spraying the tobacco with a solution of hydrogen peroxide, drying the bleached tobacco and treating the dried and bleached tobacco with a tobacco sauce containing an agent for reducing residual hydrogen peroxide.

HERMANN BAIER. 

